DIY Outdoor Lighting Tips for Beginners

• The transformer plugs into a nearby GFCI-protected outlet and reduces 120-volt current to 12 volts.
• The low-voltage cable carries current between the transformer and the light fixtures.
• The light fixtures get connected to the cable with wire connectors made specifically for outdoor use.

You can buy complete ground-level landscape lighting kits at home centers. Kits are convenient and adequate if you only need a few fixtures. But the transformer—sometimes called a power pack—will be too small if you decide to add more fixtures down the road, and style options for fixtures will be much more limited with a kit. For a deck lighting system, plan to buy individual components.

Some landscape lighting kits have preinstalled quick connectors, but they aren't what the pros use. Cheap connectors buried underground will work for a while, but they can corrode over time and fail. Cut off the factory-installed connectors and make splice connections using gelfilled wire connectors made specifically for outdoor use.

Before you buy anything, make a sketch of your deck or patio on graph paper (or use a program like Sketch-Up) and plan the location for each of your new light fixtures. To get an idea of the effect a fixture will give, pick up a clamp light—the kind with a metal reflector shade—and a few different types of lightbulbs with different brightnesses. Then, when it starts to get dark, try out the clamp light using different bulbs in a few different spots so you can observe their effect. Mark the most desirable locations on your drawing, and pay particular attention to lighting areas like stairs and transitions to different levels for safety.

Any older low-voltage transformer can be used to power both halogen and LED lights—even if they're mixed on the same circuit—as long as you have enough wattage to spare in your old transformer. If your transformer isn't big enough to handle the additional load, add a second transformer or upsize your existing one.

To prevent making your walkway look like an airport runway, stagger lights so they're not perfectly parallel.

A 'low-voltage' lighting system starts with a transformer plugged into a GFCI-protected receptacle. The transformer's job is to convert 120-volt household current to 12 volts before sending it through special outdoor cable to light your fixtures. Just a few years ago, you would have needed a 600- to 1,200-watt transformer to light a yard full of halogen lamps. But because LEDs use fewer watts than their halogen predecessors, smaller transformers—45 to 300 watts—are usually all that's needed.

So how big should you go? Just do the math! Simply add up the wattage for all the light fixtures you're planning to install, and use that number to pick the right transformer. Buy one slightly bigger than you need in case you decide to add fixtures in the future.

If you need to run wiring under an existing walkway, try this trick: Dig a small trench on both sides. Next, flatten the end of a piece of rigid metal conduit and use a sledgehammer to drive the conduit, flattened end first, horizontally under the walkway. Then cut off the ends of the conduit with a hacksaw, file off the sharp edges and feed your wire through the conduit. A 10-ft. stick of rigid steel conduit (the thick, heavy-duty stuff) is inexpensive and available at home centers.